Is September's Harvest Moon A Supermoon? Yes And No

What’s in a name? Astrologers and astronomers are having a bit of a debate about that when it comes to the difference between the big, orange harvest moon on Sept. 16, and a trifecta of supermoons to follow in October, November and December.

The upcoming harvest moon, so named because it’s the closest full moon to the fall equinox on Sept. 22, will be especially bright this year because it’s near perigee. What’s that, you who slacked in science class, ask? A moon is in perigee when it’s at the closest point to Earth in its monthly orbit.

The Harvest Moon will make an appearance at 4:05 p.m. Pacific Time on Sept. 16. Perigee comes around 2 p.m. Pacific Time on Sept. 18.

“So, it’s not the biggest possible Moon on our sky’s dome, but it’s slightly bigger than usual,” Earthsky.org explained on its website. “Still, in any year you might think the Harvest Moon looks bigger or brighter or more orange.”

Why is that?

“The orange color of a moon near the horizon is a true physical effect,” Earthsky.org went on. “It stems from the fact that — when you look toward the horizon — you are looking through a greater thickness of Earth’s atmosphere than when you gaze up and overhead. The atmosphere scatters blue light – that’s why the sky looks blue. The greater thickness of atmosphere in the direction of a horizon scatters blue light most effectively, but it lets red light pass through to your eyes. So a moon near the horizon takes on a yellow or orange or reddish hue.”

• Also See: When Does Daylight Saving Time 2016 End?

So, if the moon is bigger, why isn’t it a supermoon?

Actually, it’s not bigger. It’s what the French call trompe l'oeil, or “fool the eye,” and what astronomers call a “moon illusion.”

Astrologer Richard Nolle, who coined the term supermoon, says the Sept. 16 harvest moon doesn’t qualify under his definition of a full moon that occurs at or near — within 90 percent — of its closest approach to Earth in a given orbit.

However, astrophysicist Fred Espenak, a NASA scientist emeritus, lists the Sept 16, Oct. 16, Nov. 14 and Dec. 13 full moons as supermoons, and also includes the January 2017 full moon on the list.

Their disagreement comes from ambiguity on how “90 percent of perigee” is measured.

Regardless of which definition you accept, the Sept. 16 harvest moon should be a stunner — if the weather cooperates. Check your local forecast here.

When Is the Next Meteor Shower?

There are several more meteor showers this year, including the Nov. 16-17 Leonids, which have created some of the greatest meteor storms in history with thousands of meteors per minute during a span of 15 minutes.

Also, the Dec. 13-14 Geminids are usually regarded as one of the finest meteor showers of the year, but the Dec. 13 supermoon could wash them out.

Here’s the meteor shower calendar through 2016.

Oct. 7, Draconids: This shower favors the Northern Hemisphere. What sets this shower apart from others is that the Draconids are most likely to fly in the evening hours. It’s usually a sleeper, earthsky.org says, but in rare instances, the constellation Draco the Dragon in the northern sky can fire off hundreds of meteors in a single hour. A waxing crescent moon could intrude some on this shower.

Oct. 20-21, Orionids: The glare of a waning gibbous moon in the early morning hours just before sunrise could intrude on the Orionids, which typically produce 10 to 20 meteors per hour. Most meteors in this shower tend to fall after midnight, and they’re typically at their best in the wee hours just before dawn. The Orionids also sometimes present bright fireballs.

Nov. 4-5, South Taurids: Though the best viewing conditions are likely to be after midnight on Nov. 5, the Taurids are very long-lasting, from Sept. 25-Nov. 25. They only offer about seven meteors an hour, but the Taurids are known for having a high percentage of fireballs. This is the first of two Taurid meteor showers, and it always adds a few more meteors to the South Taurids’ peak night.

Nov. 11-12, North Taurids: This shower is long-lasting, too, from Oct. 12-Dec. 2, but modest as well with only about seven meteors an hour, with most of the activity taking place around midnight. The meteors are slow moving but very bright. The waxing gibbous moon could outshine this year’s shower.

Nov. 16-17, Leonids: Some of the greatest meteor storms in history have been associated with his event, which can produce rates of thousands of meteors per minute during a span of 15 minutes, as occurred on Nov. 17, 1966. “Some who witnessed the 1966 Leonid meteor storm said they felt as if they needed to grip the ground, so strong was the impression of Earth plowing along through space, fording the meteoroid stream,” earthsky.org says. In most years, though, the constellation of Leo the Lion whimpers rather than roars, producing about 10 to 15 meteors an hour, especially just before dawn this year. Unfortunately, the bright light of a waning gibbous moon will offer some competition.

Dec.13-14, Geminids: The last meteor shower of the year is usually one of the finest meteor showers visible in either the Northern or the Southern Hemisphere, but a full moon will be out all night, subduing the typically prolific Geminids, which can produce up to 120 meteors per hour. The shower peaks around 2 a.m.

Dec. 21-22, Ursids: This minor meteor shower often goes unnoticed. Produced by the dust grains left behind by the comet Tuttle, it produces only about five to 10 meteors an hour. The shower runs from Dec. 17-25, but it should peak around the 21st. The moon will be 23 days old at the time of peak activity, so it shouldn’t present too much of a problem.

• Also see: Wildflower Thought To Be On Brink Of Extinction Found Thriving In Contra Costa County

By Beth Dalbey (Patch Staff)/Photo by Sandy Auriene Sullivan via Flickr Commons